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The origin and evolutionary significance of triploid hybrids in diploid-tetraploid contact zone in Tripleurospermum inodorum
Ryšavá, Hana ; Čertner, Martin (advisor) ; Chrtek, Jindřich (referee)
The presence of triploid individuals, whether hybrids arising from crosses of diploid and tetraploid plants, or spontaneously generated triploid hybrids diploid populations, is increasingly important in plant populations. However, the possible evolutionary role of the triploid hybrids is closely connected to the frequency of their occurrence, to their relative fitness (compared to parental cytotype) and fertility. As a model plant I choosed Tripleurospermum inodorum, in which a relatively frequent occurrence of triploid hybrids was documented in mixed populations of tetraploids and diploids. This annual plant achieves realy quick its reproductive maturity and is easily cultivated, making it an ideal model for cultivation and pollinating experiments. Compared to parental cytotypes, the triploid hybrids of T. inodorum take approximately the same (mostly mediated) fitness values. In vitro conditions were cultivated to measure of germination rates. Germination rate of triploid seeds was comparable to diploid parental cytotype. In the subsequent comparative cultivation, nearly 150 plant individuals (2x, 3x, 4x, and aneuploid cytotype) in the greenhouse showed that the triploids had intermedial values of their parental cytotypes or close to one of the parents. Thus, the vitality of the triploid plants is...
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Variation and interspecific hybridization of Elymus repens and E. hispidus
Bartošová, Romana ; Urfus, Tomáš (advisor) ; Chrtek, Jindřich (referee)
Family Poaceae is one of the most derived groups of monocots. Major mechanisms of grasses evolution and particularly of tribe Triticeae and genus Elymus are polyploidisation and hybridisation. Presented diploma thesis assessed frequency and direction of hybridisation between Elymus hispidus and E. repens in Central Europe. Thesis also evaluated evolutionary importance (significantly higher ratio of hybridisation and polyploidisation) of hybrid swarm in Nature Reserve Čertoryje (Bílé Karpaty Mountains/the White Carpathians, the Czech Republic). Putative hybridizing populations were 14,4 % of sampled localities, i.e. direct presence hybrids (7,9 %) or both parental species (8,4 %). Aneuploids and higher polyploids were found exclusively in Čertoryje hybrid swarm, except one putative DNA nonaploid plant. The genome in situ hybridisation confirmed and improved knowledge of particular species/cytotypes chromosome counts and further specified their genome composition. GISH newly characterized genome composition of interspecific hybrids and higher allopolyploids and revealed their heterogeneous origin. Flow cytometry revealed continuum of absolute genome sizes among parental species and their hybrid. The continuum was rather asymmetric in direction towards E. hispidus. Model hybrid swarm Čertoryje produce...
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Differentiation in the polyploid complex Libanotis pyrenaica (Apiaceae)
Přívozníková, Hana ; Chrtek, Jindřich (advisor) ; Vít, Petr (referee)
Polyploidization belong to principal evolutionary mechanisms in plants. Although it is rather rare in the family Apiaceae, there are several interesting polyploid complexes here. The present study deals with Libanotis pyrenaica, species three previously reported ploidy levels, namely diploid (2n = 2x = 22), tetraploid (2n = 4 x = 44) and most likely very rare triploid (2n = 3x = 33). The present study aims at geographical pattern of ploidal diversity in central Europe, genetic variation and selected biological features of this species. Flow cytometru, analysis of two chloroplast DNA markers (trnF-trnL and cp018-cp020), morphometrics and in vitro germination experiments were used. The tetraploid cytotype occurs throughout the studied area; in the Czech Republic it was found in the České středohoří Mts., southern Bohemia and Moravia, in Slovakia it especially in the Carpathian mountains in western and central parts of the country and in the Pieniny Mts. in the northeast. Tetraploid cytotype occurs mainly in central-east Europe; in the Czech Republic it is common in the lowlands along the river of Labe and locally in Moravia; in Slovakia it was found along the river of Váh, in the Slovenské rudohorie Mts. and in the Belanské Tatry Mts. A mixed-ploidy population (2x, 4x) was discovered in southern...
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Pollination of Clusia blattophila: Quality and quantity components of the plant-pollinator system
Pinc, Jan ; Vlasáková, Blanka (advisor) ; Chrtek, Jindřich (referee)
This work discusses the pollination system of Clusia blattophila on the Nouragues inselberg in the central part of French Guiana. The pollination system is unique, because one of the pollinators is probably a cockroach species, Amazonina platystylata. It is the third, and the last known case of cockroach pollination. Flowers are also visited by crickets (Gryllidae), flies (Diptera) belonging to the families Hybotidae, Cecidomyiidae, Dolichopodidae, and some other arthropods. This work deals with the effectiveness of the pollination system and its two components. The quantitative component of the pollination effectiveness is characterized by the number of visits and visit duration. A qualitative characteristic of pollination is characterized by the number of pollen transferred by individual pollinator. To determine quantitative characteristics, ca. 450 hours of recordings were taken. From the recordings, it is apparent that cockroaches and dipterans occur on flowers more frequently, and also that cockroaches and crickets spends on flowers more time. To determine the quantitative characteristics, pollen load on stigma and insect was determined and an exclusion experiment was performed when only some floral visitors were allowed to touch the flowers. All experiments confirm that cockroach Amazonina...
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Evolutionary history of tetraploid representatives Galium pusillum group (sect. Leptogalium) in central Europe. Allopatric differentiation of Czech endemic species G. sudeticum
Knotek, Adam ; Kolář, Filip (advisor) ; Chrtek, Jindřich (referee)
The presented study tries to reveal the evolutionary history of polyploid complex Galium pusillum aiming on a rare czech endemic species G. sudeticum, an ideal model to study allopatric speciation in the context of Central European (post)glacial development. The species G. sudeticum grows in Krkonose Mts. and on serpentines in western Bohemia (Slavkovský les) more than 200 kilometers away. Our morphological and molecular data suggest a clearly different history of its two isolated areas. The populations in Krkonose Mts. are probable relics of mountainous species G. anisophyllon which was there on its northern border of occurence and hybridized with lowland species G. valdepilosum during postglacial vegetations shifts. This fact is well supported by intermediate position of Krkonose Mts. populations in both morphological and molecular AFLP analyses and by sharing the same chloroplast haplotype with geographically close lowland populations. On the other hand the serpentine lowland populations in western Bohemia are both morphologicaly and genetically indistinguishable from G. valdepilosum. Distinct genetic lineage of few populations belonging to G. valdepilosum (incl. one traditionaly referred as G. sudeticum) was found in western Bohemia and Bavaria, located on relic stands (calcareous and serpentine...
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Differentiation within the Carlina vulgaris complex in central Europe
Mašková, Hana ; Kaplan, Zdeněk (advisor) ; Chrtek, Jindřich (referee)
The Carlina vulgaris complex includes in central Europe several forms with specific morphology, ecology and distribution. Their mutual relationships and ancestry are unclear. This fact leads to many different views on their taxonomy. The critically endangered endemic taxon C. biebersteinii subsp. sudetica was described from the Czech Republic. Its differentiation from other central-European populations has not been studied yet. For this reason, my following master thesis will focus on taxonomic re-evaluation of this complex by means of investigation of genetic and morphological variation. Powered by TCPDF (www.tcpdf.org)
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Generic classification in the tribe Triticeae focused on couches (Elymus L.) in Central Europe
Bartošová, Romana ; Krahulec, František (advisor) ; Chrtek, Jindřich (referee)
Tribe Triticeae is a polyphyletic taxon in the Poaceae family which contains both perrenial and annual species, cultivated cereal crops (Triticum, Secale, Hordeum) and weeds (Elymus, Elytrigia, Aegilops). The tribe was first recognized and described at the beginning of 19th century and its genera composition have been changed many times since. As the tribe's genera are not monophyletic, its interpretation is problematic and it is also difficult to clarify evolutionary relationships among genera and species mainly in genus Elymus. Historical classification of species Elymus repens and Elymus hispidus is difficult due to morfological similarities and genomic divergence. These species are classified into many genera. Species' genome analyses were first performed in the 30's of 20th century mainly within the research of plant breeding and hybridization among cultivated cereal crops and species of distinct genera. The most important and complete papers with species and genera genome combinations were published by Löve and Dewey. Other plant scientists continued in their footsteps. Genome constitutions of all allopolyploids of Triticeae are not yet known. There is no satisfactory classification of the tribe which would well characterize their fylogenetic relationships.
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Assessing the threat of hybridization between Prunus fruticosa and cultivated Prunus species
Musilová, Lenka ; Vít, Petr (advisor) ; Chrtek, Jindřich (referee)
Presented thesis evaluates the risk of ongoing hybridization (antropohybridization) in highly endangered Prunus fruticosa in the Czech Republic and selected adjacent countries. Absolute genome size analysis (estimated by flow cytometry) combined with both numeric and geometric morphometrics were used for evaluation of hybridization. Prunus fruticosa frequently hybridize with naturalized Prunus cerasus (emerging tetraploid hybrid Prunus ×eminens) and native Prunus avium (forming triploid hybrid Prunus ×mohacsyana). Discrimination between P. ×eminens and P. ×mohacsyana is difficult, when using leaf morphology characters only, so the occurrence of triploid hybrids was strongly underestimated in the Czech Republic (only tetraploid hybrids were reported). Both hybrids are surely differentiated using flow cytometry analysis (based on different ploidy level). The majority of analyzed populations is formed by either individuals of pure P. fruticosa or one of the mentioned hybrids. Only four populations were mixed. Continuous variability in absolute genome size was found in two of them, which may indicate hybrid swarm forming (incl. primary hybrids and backcrosses). Our findings can be considered only as indirect evidence for introgression, which needs to be confirmed by molecular markers (for example...
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